Target for producing neutrons

ABSTRACT

A target for producing neutrons is composed of layers of hydrides mounted on a plate impermeable to hydrogen. This increases the life of the target.

iiniiefi Siaies Pawn [191 Fabian 1 0d. 16, 1973 [54] TARGET FOR PRODUCING NEUTRONS 3,591,812 7/1971 Detaint 250/845 [75] In entor Hans Fabian Gustav, Germany 3,183,356 5/1965 Cherubmi 250/845 [73] Assignee: Nukem Nuklear-Chemie und Metallurgie Main, Primary Examiner-James W. Lawrence Germany Assistant ExaminerDavis L. Willis Attorney-Francis D. Stephens and Hu 0 Huettig, Jr. [22] Filed. Feb. 2, 1971 g [21] Appl. No.: 111,821

[30] Foreign Application Priority Data 7 [57] ABSTRACT Feb. 2, 1970 Germany P 20 09 049.7

52] us. Cl 25137159 313761 s A targetfmpmducing neutwns is C0111pOsed of layers [51] Int. Cl G21g 3/04 of hydrides mounted on a plate impermeable to hydro {58] Field of Search 250/84.5, 84; This increases the life the 5 Claims 1 Dra n Fi are [56] References Cited WI g g UNITED STATES PATENTS 3,320,422 5/1967 St. John 250/845 PMENIED U 15 I973 766.389

INVENTOR Hans Fabian TARGET FOR PRODUCING NEUTRONS This invention relates to a target composed of layers of various metal hydrides for the production of neutrons.

l4 MeV-neutrons are created with tritium T (d,n) He is bombarded with deuterium. The deuterium is introduced into the vacuum as an ionized gas and the tritium is installed as a hydride in a solid form. Carrier or support particles for the tritium are customarily of metals or metal alloys whose hydrides provide a high content of hydrogen. The number of neutrons that are produced depend upon just how many tritium atoms are hit by the deuterium ray when it penetrates into the target. Since the cross-section of the effect of the T-D reaction is extremely small, it is known that only a fraction of the deuterium bombarding and penetrating the target is used for producing neutrons. The remaining and larger portion of the deuterim entering the target remains there.

The above method for producing neutrons has the inherent disadvantage that more and more deuterium is collected in the target during the increasing time in which the target is bombarded by the deuterium ray. However, since the target is already a saturated hydride, which means it is loaded with tritium, and since, in addition, during the deuterium ray bombardment, hydrogen is constantly introduced as deuterium, it is absolutely necessary that hydrogen must escape from the target. This loss of hydrogen is usually a mixture of tritium and deuterium and leads to the fact that the target becomes poor or lacking in tritium and that consequently, following this hydrogen loss, the neutron yield is greatly reduced.

The object of this invention is to produce a target whose life span is considerable lengthened.

In general, this object is obtained by using two or more hydrides, for example titanium hydride, scandium hydride and erbium hydride, all having different disintegration temperatures, mounted on a support plate that is impermeable to hydrogen, for example, a copper plate with the hydrides being mounted on the plate in layers one upon the other. The disintegration of titanium hydride beings of approximately 200 C, while scandium hydride and erbium hydride resist disintegration until a temperature of approximately 400 C is reached.

The thickness of the hydride layers is, preferably, such that at least one layer is not reached by particles bombarding the target. The hydrides preferably have an atomic ratio of hydrogen to hydrogen, for example, H/Ti, which is greater than 1.

The means by which the objects of this invention are obtained are described more fully with regard to the accompanying schematic drawing of the target. On copper plate 1 is mounted a titanium hydride layer 2, upon which is an erbium layer 3. A water spray nozzle 4 or other cooling means is positioned on the side of the plate 1 opposite to that with which the target is bombarded in order to reduce the heat produced by the bombardment. A thermocouple 5 is mounted on the target for measuring the target temperature. The thickness of the erbium hydride layer 3 is such that during the bombardment in the accelerator apparatus, the deuterium is completely stopped in the erbium hydride layer. However, in order to prevent dispersal, it is also possible to add another layer 6 composed, for example, of scandium or aluminum.

OPERATION OF THE TARGET During deuterium ray bombardment the target is being heated. By using a suitable and controlled cooling process the medium temperature of the target can be held to about up to 300 C. The pressure of disintegration in the titanium hydride is very large at this temperature. The titanium hydride layer tries very hard to give off tritium. On the other hand, the erbium hydride layer is completely disintegration resistant at 300 C. Since copper plate 1 is practicallycompletely impermeable to hydrogen, it is possible for the tritium freed from the titanium hydride to be diffused in the erbium hydride. By suitably varying the cooling of the target and the load on the surface (with the aid of ion'optics it is possible to focus or de-focus the deuterium ray), it is possible to control the tritium diffusion. in such a way that the deuterium used for the bombardment is dispersed or displaced from the erbium hydride layer so that, in a balanced condition, only a small concentration exists in the erbium hydride layer.

Having now described the means by which the objects of this invention are obtained,

I claim: I

1. A target for the production of neutrons comprising a support plate impermeable to hydrogen, at least two separate layers of different hydrides mounted on said plate, said hydrides being selected from the group consisting of titanium hydride, scandium hydride and er: bium hydride, and in which the temperature stability in the layers of hydride decreases toward'said'support plate.

2. A target as in claim 1, said hydrides having a disin tegration temperature of at least about 500 C. r

3. A target as in claim 1, said hdyrides having a difference in temperature disintegration from o'ne'anotherof at least about 50 C.

4. A target as in claim 1, in which the thickness of I' said layers is such that at least one layer is not reached by particles bombarding'said target. I v

5. A target as in claim 1, in which said hydrides have an atomic ratio of hydrogen to hydrogen carrier, as

H/Ti which is greater than 1. 

1. A target for the production of neutrons comprising a support plate impermeable to hydrogen, at least two separate layers of different hydrides mounted on said plate, said hydrides being selected from the group consisting of titanium hydride, scandium hydride and erbium hydride, and in which the temperature stability in the layers of hydride decreases toward said support plate.
 2. A target as in claim 1, said hydrides having a disintegration temperature of at least about 500* C.
 3. A target as in claim 1, said hydrides having a difference in temperature disintegration from one another of at least about 50* C.
 4. A target as in claim 1, in which the thickness of said layers is such that at least one layer is not reached by particles bombarding said target.
 5. A target as in claim 1, in which said hydrides have an atomic ratio of hydrogen to hydrogen carrier, as H/Ti which is greater than
 1. 